A closer look
The dose context changes the conversation.
Care that fits your life.Low dose naltrexone, dosed to the milligram.
Naltrexone 1.5 to 4.5 mg in a capsule formulation. Explore opioid-receptor activity and the condition-specific research behind LDN.
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Meet the formula
Low-dose naltrexone, usually shortened to LDN, describes a lower-dose formulation of naltrexone. The HealthRX.com catalog lists 1.5 to 4.5 mg capsules. Naltrexone is an opioid-receptor antagonist, meaning it blocks activity at opioid receptors. Researchers have explored lower-dose regimens in several conditions, with each study asking its own question. The useful product explanation connects the molecule, the dose context and the research endpoint, rather than using inflammation or recovery as an all-purpose label.
Naltrexone, an opioid-receptor antagonist
Lower-dose formulation; catalog range 1.5 to 4.5 mg
The condition, symptom and measured outcome
Inside the formula
1.5 to 4.5 mg catalog range
The word low describes the dosing context of an established medication. It is not a separate molecule or a new ingredient family. Conventional naltrexone products and lower-dose formulations share the active ingredient while using different amounts and clinical contexts. This capsule listing identifies the lower-dose range; research on a particular regimen belongs to that exact study, population and outcome.
A closer look / 01
Opioid receptors are part of the body’s signaling systems. An antagonist acts by blocking receptor activity, which is the pharmacologic starting point for understanding naltrexone. Lower-dose research also discusses proposed mechanisms beyond the conventional dosing context. An established receptor action and a proposed explanation for a particular use are different levels of evidence, so they deserve distinct treatment in a clear product guide.
That distinction helps keep the page useful. Knowing the ingredient family explains what naltrexone is. Knowing the strength and formulation explains the product. Naming the target symptom explains what a treatment discussion is trying to assess. Those three pieces make a more specific story than assigning every lower-dose use the same recovery promise.
A closer look / 02
Published LDN studies include fibromyalgia and Crohn’s disease. A pain trial and an intestinal-disease trial measure different outcomes, even when both use naltrexone. Fibromyalgia research has evaluated pain scores and related symptom measures; Crohn’s research has used clinical and intestinal-disease assessments. These are separate research settings rather than one general wellness outcome.
The findings also differ across studies. A 2024 randomized fibromyalgia trial of 6 mg daily did not show superiority over placebo for its primary pain outcome. Earlier work has examined other doses and designs. The exact regimen, the comparison group and the endpoint are all useful details when interpreting this evolving research area.
A closer look / 03
The catalog range is 1.5 to 4.5 mg, with a 30-capsule listing. Strength describes the amount of active ingredient in a formulation; quantity describes the number of capsules in the catalog option. A range identifies the listed product strengths, while the selected prescribed formulation provides the specific product context. Comparing those details is more informative than reading “low dose” alone.
A closer look / 04
A useful personal record names the symptom being followed and how it is observed. Pain intensity, sleep quality, fatigue and day-to-day function describe different experiences. Following the same measure consistently makes a change easier to describe. It also keeps a goal tied to the relevant research question instead of assuming improvement in one observation means improvement in every related concern.
Make an informed comparison
These options have different active ingredients and mechanisms. LDN is a lower-dose naltrexone formulation; rapamycin is an mTOR-pathway medication; metformin is a biguanide. Their shared location in the longevity catalog is a browsing category, while their product identities remain distinct.
| Option | Ingredient identity | What distinguishes it |
|---|---|---|
| Low Dose Naltrexone | Naltrexone | Opioid-receptor antagonist; capsule formulation |
| Rapamycin | Sirolimus | mTOR inhibition; capsule formulation |
| Metformin ER | Metformin | Glucose-regulation pharmacology; ER tablet |
The useful details
LDN contains naltrexone, a medication ingredient. The lower-dose description refers to its formulation context. It does not change the molecule into a vitamin, mineral or nutritional supplement. The active name and the exact strength make that identity clear.
Researchers choose a regimen for the question and population being studied. A study at 6 mg and a catalog range of 1.5 to 4.5 mg describe different dose contexts. Following those details keeps a study result attached to the regimen that produced it.
Explore the ingredient research
See the available product options.
View optionsHealthRX.com verified facts
Low Dose Naltrexone (LDN) starts at $129 per month on 12-month plan; the lowest checkout charge is $161 (billed monthly). A prescription is never guaranteed. A licensed provider reviews each request before a pharmacy can dispense treatment.
Catalog verified August 26, 2026. Source: HealthRX.com checkout catalog and refund policy. Monthly equivalent divides the discounted plan charge by the number of months; checkout may collect a multi-month total.
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A US-licensed provider reviews your history and, if appropriate, prescribes a low starting dose off-label.
Your exact dose is compounded and ships to your door in 3 to 5 days.
Step up gradually and message your provider along the way.
Compounded by a US-licensed pharmacy to your precise low dose, usually 1.5 to 4.5 mg.
Taken once a day, most often at bedtime.
Small human trials have looked at low-dose naltrexone in fibromyalgia and Crohn's disease, summarized in the research section.
A US-licensed provider prescribes it off-label and steps your dose up gradually.
Full-dose naltrexone blocks opioid receptors. A small fraction of that dose is studied for a different effect: a brief blockade that may prompt your body to raise its own endorphins and calm inflammatory signaling. Your provider starts you low and adjusts over time, and the pharmacy compounds your exact dose.
Naltrexone is an opioid receptor antagonist, used off-label at low doses. Compounded by a US-licensed pharmacy.
A brief receptor block
At low doses, naltrexone briefly blocks opioid receptors for a few hours.
An endorphin rebound
Your body responds by raising its own endorphins.
Calmer immune signaling
Low-dose naltrexone is also thought to quiet inflammatory signaling from immune cells called microglia.
A short blockade that may prompt your own endorphins and calm inflammatory signaling. The mechanism is still being studied.
Naltrexone is an established opioid antagonist, and at very low doses it is prescribed off-label for inflammation and immune balance. The human evidence comes from small trials, summarized below. These studies are early and modest in size rather than large confirmatory trials.
28.8% vs 18.0%
Reduction in daily pain with low-dose naltrexone versus placebo in a double-blind crossover trial of 31 women with fibromyalgia.
Younger et al., Arthritis and Rheumatism, 2013
88% vs 40%
Clinical response in active Crohn's disease with low-dose naltrexone versus placebo in a randomized trial of 40 adults.
Smith et al., Digestive Diseases and Sciences, 2011
Low dose is a different tool from standard naltrexone
| Low-dose naltrexone (1.5 to 4.5 mg) | Standard naltrexone (50 mg) | |
|---|---|---|
| Dose | 1.5 to 4.5 mg | 50 mg |
| Opioid receptor block | Brief and partial | Full and all day |
| Typical use | Inflammation and immune balance, off-label | Opioid and alcohol use disorder |
| When taken | At night | Once daily, any time |
| Form | Compounded to your dose | Standard tablet |
| Goal | Endorphin rebound | Sustained opioid blockade |
Vivid dreams or lighter sleep can show up early and usually settle. Your provider tracks your response over the following weeks.
Week 1 to 2
Begin at the lowest dose, taken at night.
Week 2 to 4
Vivid dreams or lighter sleep can show up early and usually settle; some take the dose earlier in the evening.
Week 4 to 8
Your provider steps the dose toward 3 to 4.5 mg as you tolerate it.
Ongoing
Your provider tunes the dose to how you respond.
Not prescribed with opioid medication. Your provider reviews everything you take first and starts you low.
Do not take low-dose naltrexone with opioid pain medication. It can block those medicines and, if you have opioids in your system, bring on withdrawal. Tell any provider or surgeon that you take it before procedures.
An independent US-licensed clinician reviews every request. If they decide the treatment is not right for you, you get a full refund for the medication.
Prescriptions are filled by a US-licensed pharmacy and shipped free, in discreet packaging, on every plan.
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Compounded medications are prepared by a US-licensed pharmacy and are not reviewed by the FDA for safety or effectiveness. Products are dispensed only after a licensed provider determines they are appropriate. Information here is educational and is not a substitute for medical advice.
